Electrical terminal connector block



May 19, 1970 ZIELKE 3,513,434

ELECTRIAL TERMI NAL CONNECTOR BLOCK Filed Oct. 23, 1965 I 4 @mw Lnwzucs Z/ELKE INVENTOR.

AGENT United States Patent U.S. Cl. 339-18 1 Claim ABSTRACT OF THE DISCLOSURE An electrical terminal connector block which comprises a block-like body of dielectric material with an elongate access opening entering an exterior surface of the body and communicating with the cavity; and an elongate, normally unbiased helically wound, axially extensible contact spring comprising a multiplicity of convolutions defining a plurality of pairs of adjacent convolutions and arranged in the cavity to extend longitudinally therein and accessible through the access opening, the convolutions of each pair of convolutions being adapted to be yieldingly parted axially of the spring to engage and hold a wire lead extending through the access opening and into engagement with the spring; the spring being greater in outside diameter than the lateral extent of the access opening whereby it is held captive in the cavity and being less in longitudinal extent than the cavity whereby it can be freely extended axially to receive wire leads to be engaged therewith.

The invention herein described pertains to electrical terminal blocks or strips, and more particularly to what might be called bread board terminal blocks for use in making temporary connections in experimental apparatus of an electronic or other electrical nature without the use of solder, screws, Fahnstock clips or other slow or cum-' bcrsome connecting means.

The components of experimental electrical assemblies, particularly those having to do with electronic circuits, are frequently connected together merely by twisting the bare ends of the conductors together. Sometimes the experimental connections are made by means of standard terminal blocks or connector strips in which two or more binding posts, Fahnstock clips or the like are integrally connected, the leads to the various components being attached to the Fahnstock clips or their equivalents. Solder is also frequently used for experimental or other temporary connections despite the bother entailed in melting the solder if the circuit or the components are to be rearranged. One of the objects of the present invention is to make it possible to produce tight, low resistance connections without the use of any of the aforementioned devices or expedients.

Another object is to make it possible to make temporary connections very rapidly and to disconnect them almost instantaneously.

A further object is to provide a connector of the type described that may be used for either a small or large number of temporary connections.

An additional object is to provide an embodiment of the invention in which the connecting elements that are components of the device are shielded from each other.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of illustrated embodiments of the invention. For this purpose, such embodiments are shown in the drawings accompanying and forming part of the present specifications. These forms will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed de scription is not to be taken in a limiting sense, since the ice scope of the invention is best defined in the appended claims.

In the drawings:

FIG. 1 is a plan view of a portion of a connector block embodying the invention;

FIG. 2 is a section taken on line 2-2 of FIG. 1;

FIG. 3 is a perspective drawing of a segment of the embodiment illustrated in FIGS. 1 and 2, showing a pair of conductors interconnected by means of the helical spring which is a component of the device;

FIG. 4 is a view similar to FIG. 2, but showing a modified form of the invention in which the springs are confined below the top surface of the connector block; and

FIG. 5 is a view similar to FIGS. 2 and 4, showing a metal terminal block with an insulating lining.

The presently preferred embodiment of the invention comprises a block or strip of insulating material 12 having a plurality of four-sided recesses or cavities 13 therein that are open outwardly at an outer or top surface 11 of the block. If the block is to be used for interconnecting a plurality of conductors, the cavities are usually rectangular in shape, as clearly shown in the plan view. A coiled helical spring 14 of conducting material having closely wound, but not necessarily contacting, convolutions is positioned within each of the recesses, the total length ofiv each spring being less than the total length of the recess, for reasons that will hereinafter become apparent.

To obviate the necessity of an apertured covering plate to retain the springs within the cavities and yet permit I access to the springs, the presently preferred embodiment of the invention has recesses, the side walls of which are closer together at the top of the recesses than at the bottom whereby they converge with the outer or top surface of the block to define narrow access openings in said top surface communicating with the interiors of the cavities. The width of the access openings at the tops of the cavities is less than the outside diameter of the springswhereby the springs are held captive in the cavities and in order to make it impossible for the springs to fall out of the recesses if the device is turned upside down.

Unless the recesses extend to the edge of the block to permit the springs to be inserted into the recesses from the open ends thus provided, it is of course necessary that the cavities be closed at the bottom, as illustrated in FIGS. 2, 3 and 4 where a retaining plate 15 is shown in engagement with the under surface of the block 12. The retaining plate, like the block itself, is necessarily formed of nonconducting material. The plate and block may be secured together by any convenient means, such as by screws 16, one of which is shown in FIG. 2.

In one embodiment of the invention, a portion of the periphery of each of the springs extends above the top surface of the device, as illustrated in FIGS. 2 and 3. This makes the springs extremely accessible.

In order to electrically connect a pair of conductors by means of devices embodying the present invention, it is merely necessary to insert the bare end of each wire between adjacent convolutions of the spring, as shown in FIG. 3. The insertion is facilitated by using a sharp instrument to separate the convolutions. This is particularly helpful if the wires to be inserted are fragile. If additional wires are to be electrically interconnected, each is interposed between a different pair of convolutions in order to assure that the convolutions will firmly grip the conductors.

It should be clear from this illustration that the length of each recess should exceed that of the spring by the combined diameters of all the wires that can individually be interposed between respectively adjacent convolutions of the spring, and that the number of conductors that may be interconnected by means of any spring is one less than the number of convolutions in the spring. For example,

if the spring has nine convolutions, eight wires may be tightly secured and interconnected by the,spring.

If it is desired to connect morefwires together than can be interconnected by one of the springs, then twoof the springs may be electrically joined by means of a jumper wire whose bare ends are positioned between the convolutionsof different springs. 7

It should be apparent from FIGS. 2 and 3 that any bare electrical conductor engaging the portions of the periphcries of two or more of the springs that extend above the surface of the device will short circuit such springs. Where such accidental short-circuitir g is a possibility, the enibodiment of the invention shown in FIG. 4 may be used. In this emhodimenh'the side walls of the cavities 13a that converge as they approach the upper or top surface 11a of the block 12a extend sufiic'iently far above the top peripheries of the springs 14 to prevent accidental engagement with such bare metal objects as might be resting ppon the upper surface of the device. If the side walls of the cavities are spaced the same both at the top and bottom of the cavities, a top insulating plate, with a window for each of the cavities, be attached to the upper surface of the blocklZ. However, the arrangement shown in FIGS. 3 and 4 avoids the use of such a top plate and makes possible a much less expensive device, particularly if the blocks or strips 12 are molded. W n

The modification shown in FIG. 5 makes it possible to use a metal block 12c instead of the non-conducting blocks of previously described embodiments. The cavities 13b entering the top 11b of the block 12c are provided with insulating linings 18 that electrically isolate the springs in the blocks and from each other;

If the materials used for the springs 14 and the bloc}; 12 are such that the springs are not sufliciently restrained 'by friction against retation when conductors are inserted at an angle between convolutions of the spring, this tenden oy may be counteracted by straightening the ends of the spring so that they extend tangentially from the coil on its lower side, each end then acting to prevent rotation of the spring in a different direction, or a flat strip of metal may be soldered to the bottom side of the spring.

Various other modifications may of course be made from the embodiments hereinbefore described and illustrated in the drawingswithout departing from the broad spirit of the invention as succinctly set forth in the appended claim. 7

The inventor claims:

1. A terminal connecting device comprising a block of substantially rigid dielectric material with an outer surface, an elongate cavity within the blgck and an elongate access opening entering said surface and communicating with said cavity, an elongate, straight, axially extensible, helically wound contact spring in and extending longitudinally of said cavity, and resting upon the bottom wall or said cavity, the adjacent convolutions or said spring being in coextensive abutment, saidaccess opening being less in lateral extent than the outside diameter of the spring whereby said spring is held captive in said cavity and the length at said spring being sufficiently less than the length of the cavity to permit the spring to be expanded in length by a suitable tool disposed through said access opening to yieldingly receive a conductor engaged through the opening and between said adjacent convolutions of the spring, said cavity having fiat, laterally spaced, outwardly converging side walls converging with said outer surface to define said access openingf References Cited EJNITEDJ STATES PATENTS 1,466,351 3/1923 Brockett et al. 1... 3391-133 XR 2,732,534 1/1956 Giel. 3, 3,085,177 4/1963' Thompson 339-18 XR 3,150,911 9/1964 Matteson 5 339 254 MARVIN CHAMPION, Primary Examiner P. A. CLIFFORD, Assistant; Examiner Us. 01. X.R. 

